Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?

[Anthony Liguori]

On 08/04/2010 12:37 PM, Avi Kivity wrote:
>  On 08/04/2010 08:27 PM, Anthony Liguori wrote:
> > On 08/04/2010 12:19 PM, Avi Kivity wrote:
> > >  On 08/04/2010 08:01 PM, Paolo Bonzini wrote:
> > > > That's another story and I totally agree here, but not reusing 
> > > > /dev/sd* is not intrinsic in the design of virtio-blk (and one 
> > > > thing that Windows gets right; everything is SCSI, period).
> > >
> > > I don't really get why everything must be SCSI.  Everything must 
> > > support read, write, a few other commands, and a large set of 
> > > optional commands.  But why map them all to SCSI?  What's the magic?
> >
> > Because that's what real hardware with only a few rare exceptions.
>
> I thought that IDE was emulated as SCSI even when it wasn't.  But I 
> guess now with SATA you're right.

IDE -> EIDE -> ATA -> SATA

ATA can encapsulate SCSI commands via ATAPI which gives you the ability 
to have ATA based CD-ROMs among other things.

I don't believe that SATA actually uses SCSI commands for read/write 
operations but I think Linux exposes SATA drivers as SCSI anyway.

Regards,

Anthony Liguori